Wesley and Mark took part in a 42 km marathon. Wesley ran half the distance at a speed of 9 km/h and ran slower for the rest of the way at a speed of 9 km/h. Mark ran half his total time at 10 km/h and ran slower for the rest of the time at 5 km/h. If they started the marathon at 3.30 a.m., at what time would each of them finish?
- Wesley
- Mark
(a)
Half of the 42 km marathon = 42 ÷ 2 = 21 km
Time taken by Wesley for the first half of the marathon
= 21 ÷ 9
= 2
13 h
Time taken by Wesley for the last half of the marathon
= 21 ÷ 9
= 2
13 h
Total time taken by Wesley
= 2
13 + 2
13= 4
23 h
1 h = 60 min
23 h =
23 x 60 = 40 min
4
23 h = 4 h 40 min
4 h 40 min after 3.30 a.m. = 8.10 a.m.
Time that Wesley would finish the marathon = 8.10 a.m.
(b)
Time taken by Mark for the first half of the marathon
= 21 ÷ 10
= 2
110 h
Time taken by Mark for the last half of the marathon
= 21 ÷ 5
= 4
15 h
Total time taken by Mark
= 2
110 + 4
15 = 6
310 h
1 h = 60 min
310 h =
310 x 60 = 18 min
6
310 h = 6 h 18 min
6 h 18 min after 3.30 a.m. = 9.48 a.m.
Time that Mark would finish the marathon = 9.48 a.m.
Answer(s): (a) 8.10 a.m.; (b) 9.48 a.m.